docs: def display_missing(self, data, return_bool="any"):
          """ ???
          
          Parameters
          ----------
          data            : pd.DataFrame()
              Input dataframe.
          return_bool     : bool
              ???
  
          Returns
          -------
          pd.DataFrame()
              ???
  
          """
  
          if return_bool == "any":
              bool_sel = self._find_missing(data, return_bool="any")
  
          elif return_bool == "all":
              bool_sel = self._find_missing(data, return_bool="all")
  
          return data[bool_sel]